The rectifier circuit is a circuit that converts alternating current (AC) electrical energy to direct current (DC) electrical energy. The rectifier bridge is the most common circuit that utilizes the property of one-way conduction of the diode to perform rectification, and is often applied to convert AC to DC. Under certain occasions, the circuit that is before the rectifier bridge (before-bridge circuit) needs to be controlled. For example, in the implementation of a dimmer circuit, the connection and disconnection of the damper circuit needs to be controlled flexibly based on the type of the dimmer. When a leading edge dimmer is connected before the rectifier bridge, a damper circuit needs to be connected before the rectifier bridge to yield satisfying dimming effects. When a trailing edge dimmer is connected before the rectifier bridge, the damper circuit before the bridge needs to be disconnected. Otherwise, operations of the dimmer may become abnormal under certain conditions (e.g., the load reduces), resulting in the failure of the circuit, which damages the device.
Commonly, since the AC circuit before the rectifier bridge and the DC circuit after the rectifier bridge have different reference voltages, different methods are used to control and adjust the AC circuit before the rectifier bridge and the DC circuit after the rectifier bridge, respectively. Therefore, the circuit after the rectifier bridge cannot be applied to control and adjust the circuit before the rectifier bridge.